JP2003260585A - Method and apparatus for joining solids by pulse energization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid joining method which enables the formation of a joint face which is stronger and more reliable than conventional joining methods such as discharge plasma sintering. <P>SOLUTION: This solid joining method for joining members 1, 2 to be joined by pulse energization includes the steps of: butting a joining face of a first member against a joining face of a second member (butting step; step S1); forcibly heating the joining faces of the butted members externally (forced heating step; step S2); allowing a pulsed current to flow through the joining faces while pressing the heated joining faces against each other to temporarily join the joining faces to each other (pressing/pulse energization step; step S3); and heat-treating the temporarily joined members under predetermined temperature conditions (heat treatment step; step S4). It is confirmed that a strong and reliable joint state can be formed which, as compared with the conventional methods, has improved bonding strength of the joint face which is approximately equal to the strength of the base materials of the members to be joined. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to pulse energization capable of joining a joining surface with a joining force about the strength of the base metal of the member by performing pulse energization while pressing the joining surface of the members to be joined with a predetermined force. The present invention relates to a solid bonding method and a solid bonding apparatus.

[0002]

2. Description of the Related Art As a method for joining solids to each other, there is a method described in Japanese Patent Application Laid-Open No. 2002-059270. In the method described in this publication, the joining surfaces of the members to be joined are butted against each other, and in this state, a pulse current is applied to the joining surfaces while applying a predetermined pressing force to the joining surfaces, and the joining surfaces are temporarily joined. Then, the joint surface is heat treated to form a strongly joined joint surface.

According to this method, solids can be firmly bonded to each other, but there are some points to be improved such as discontinuity of the structure remaining at the bonded interface after the bonding. Moreover, a new joining method for surely joining solids is being demanded.

An object of the present invention is to propose a new solid bonding method and apparatus capable of securely bonding solids to each other with a strong bonding force of the strength of the base material of the bonding member.

[0005]

With reference to FIG. 1, a solid joining method of the present invention is a butting step of butting the joining surfaces of at least a first member and a second member, which are objects to be joined. (Step S1), a forced heating step of locally forcibly heating the joint surfaces of the abutted members (step S2), and a pulse current through the joint surfaces while pressing the joint surfaces in a heated state with each other. Flow, and a pressing / pulse energizing step (step S) for temporarily joining the joining surfaces.
3) and a heat treatment step (step S4) of heat-treating the temporarily bonded member under a predetermined temperature condition.

According to the method of the present invention, the joint strength of the joint surface is improved as compared with the conventional method, the degree of discontinuity in the structure of the joint surface remains less, and the strength of the base metal of the joint member is about the same. It was confirmed that it is possible to form a strong and reliable joined state having the joining strength of. Although the clear reason why such a desirable joining state is formed is not clear, the joining interface is activated by locally forcibly heating the joining surfaces in a butt state from the outside and performing pulsed current flow, and A synergistic effect is obtained in which oxides are removed, cleaning of the bonding interface is promoted, formation of interface bonding sprouting is promoted, and diffusion of the formed interface bonding sprouting is promoted. Therefore, it is considered that a joint surface that is reliably joined is formed.

Here, in the forced heating step (step S2), 55% of the melting points of the members to be joined having the lowest melting points.
It is desirable to heat the joint surface to a temperature within the range of 90%. If the temperature is less than 55%, the above synergistic effect cannot be sufficiently obtained, and if it exceeds 90%, the joint surface in the pressed state may be plasticized, which is not practical.

The heating time in the forced heating step is
Although it depends on the heat capacity of the joining member, it is generally 60 minutes or less.

Similarly, the pressing force in the pressing / pulse energizing step (step S3) also varies depending on the hardness of the joining member, the surface roughness of the joining surface, the joining temperature, etc., but generally 1 to 7
The pressing force may be within the range of 00 MPa.

Further, as the pulse current, generally, a duty ratio (pulse on / off ratio) is 50% or more, a voltage is 100 V or less, and a current value is 100 A to 50,000 A.
A pulse current within the range of may be used.

The heat treatment temperature in the heat treatment step (step S4) is 55, which is the melting point of the members to be joined having the lowest melting point.
It is desirable to set the temperature within the range of 90% to 90%. 55
If the temperature is less than%, sufficient thermal diffusion of the joint surface cannot be expected,
If it exceeds 90%, there is a possibility that adverse effects such as characteristic changes due to softening of the joint surface may occur, which is not practical.

Further, the heat treatment time in the heat treatment step varies depending on the heat capacity of the joining member and the like, but is generally 60 minutes or less. Furthermore, it is desirable that the heat treatment process be performed in vacuum.

Next, according to the test by the present inventors, in order to further enhance the above-mentioned purification of the joint interface, the formation of the joint sprouts at the interface, and the diffusion of the interfacial joint sprouts, the butt step (step Prior to S1), it is desirable to perform a bonding surface treatment step (step S0) of subjecting at least one of the bonding surfaces of the first member and the second member to surface treatment. Was confirmed. It has been confirmed that it is particularly desirable to form a thin film on the joint surface.

It is desirable that at least a part of the components of the thin film is the same as the bonding surface on which the thin film is formed. Further, it is more preferable to form the same thin film as the bonding surface. Such a thin film diffuses and disappears in the base material structure of the joining member in the joining process, and a strong and surely joined joint surface is formed.

For example, as schematically shown in FIG. 2A, the first member 1 and the second member 2 to be joined are made of the same material A.
In such a case, thin films 3 and 4 made of the same material are formed on the bonding surfaces 1a and 2a, respectively, and the bonding surfaces of these thin films are used as the bonding interface 5. In this case, as schematically shown in FIG. 2B, these thin films 3 and 4 diffused and disappeared in the respective members 1 and 2 during the treatment process, and were firmly and reliably joined. The joint surface 5a is formed.

Further, as schematically shown in FIG. 3 (a), when the first member 1 and the second member 2 to be joined are made of different materials A and B, their joining surfaces 1a, Thin films 6 and 7 made of the same material as the respective members are formed on 2a, and a bonding surface of these thin films serves as a bonding interface 8. Also in this case, as schematically shown in FIG. 3 (b), these thin films 6 and 7 diffuse and disappear into the respective members 1 and 2 in the process, and are firmly and surely joined. The joined surface 8a is formed.

Next, the thin film may contain a component capable of permeating and diffusing into the joint surface. Furthermore, the thin film may contain a reducing component.

Here, the thickness of the thin film is generally 0.0
It may be in the range of 1 to 10 μm. If it is less than 0.01 μm, the effect of thin film formation cannot be expected, and it is 10 μm.
If the thickness exceeds, the thin film may remain on the joint surface.

Although any method may be used for forming the thin film, it is preferable to use the sputter vapor deposition method which can easily control the film thickness and can form a uniform thin film.

Next, as a joint surface treatment step, a polishing treatment for increasing the smoothness of the joint surface can be performed.
In this case, when the joining material is an iron-based material, it is desirable that the surface roughness of the joining surface is finished to a mirror surface with Ra = 0.3 or more by the polishing treatment. A material having a hardness lower than that of an iron-based material such as copper or aluminum may have a rougher surface roughness than this.

Further, as the joint surface treatment step, a cleaning treatment for washing the joint surface can be performed.

Next, the joint surface treatment step may include processing for processing into a complementary joint surface shape so that the joint surface of the first member and the joint surface of the second member are in close contact with each other. is there. For example, when the joining surface of one joining member is a convex curved surface, it is desirable to adopt a concave curved surface that comes into close contact with this as the joining surface shape of the other joining member.

Next, the present invention relates to a bonding apparatus for bonding solids by the above-mentioned solid bonding method using pulsed current. With reference to FIG. 4, the joining device 10 according to the present invention comprises a joining surface 1 of the first member 1.
a and the joint surface 2a of the second member 2 are held in abutment with each other, and pressing means 11 capable of pressing these joint surfaces 1a and 2a with a predetermined pressing force; and the joint surface 1a in the abutted state, External heating means 12 for forcibly heating 2a from the outside
An energizing means 13 for passing a pulse current through the joint surfaces 1a, 2a in a butt state, and a heat treatment means (12, 1) for heat-treating the first and second members 1, 2 in a temporary joint state.
4)) and are featured.

The heating element 21 of the external heating means 12 may be any one or a combination of electric resistance heating, microwave heating, glow discharge heating, high frequency heating, energization heating, impulse heating and infrared heating. it can.

Further, it is desirable that the external heating means 12 be capable of performing local forced heating on the joint surface and overall heating of the members in the butted state. In this case, the local forced heating and the whole heating may be switched.

Further, the external heating means 12 is provided with a cover 22 corresponding to the shape of a joining member such as a cylinder surrounding the joining surfaces in a butt state, and a heating element 21 built in the cover 22. It can be configured.

In this case, the external heating means 12 is the cover 2
It is desirable to include the cover guide mechanism 23 that can adjust at least one of the arrangement position and the angle of the two. With this configuration, the heating element can be positioned at the position corresponding to the bonding surface position.

Next, there is a processing chamber 15 in which the first and second members 1 and 2 held in abutting state by the pressing means 11 are arranged, and in this processing chamber 15, the joint surface is forcibly heated and pressed. By performing heat treatment and heat treatment, treatment efficiency can be improved.

In this case, if the external heating means 12 and the heat treatment means are used in the same manner as in the illustrated example,
The device configuration can be made compact and inexpensive.

In this case, the external heating means provided with a single power source may be switched and controlled so that the local forced heating of the joint surface and the overall heating during the heat treatment are performed.

When the heat treatment is performed in an inert atmosphere such as a vacuum, a vacuuming device 14 for vacuuming the inside of the processing chamber 15 may be arranged.

Here, in the illustrated example, the pressing direction by the pressing means is perpendicular to the joining surface and is the same as the pulse energizing direction, but the pressing direction and the pulse energizing direction are different depending on the joining surface shape. In some cases,

The energizing means 13 can be composed of a pair of electrodes 31, 32 and a pulse current supply source 33. When energizing in the atmosphere, the energization may be performed by sandwiching the periphery of the members to be joined with an electrode cord. Also, the electrode 3
1 and the joining member 2, between the electrode 32 and the joining member 1,
It is also possible to interpose a heat-resistant and pressure-resistant heat generating member that can be energized. Such a member can be formed using carbon, molybdenum, or the like. In addition, the shape of such a member is generally such that the joint surface between the electrode and the joint member is flat. However, when the end surface shape of the joining member is a convex shape, a concave shape, or an inclined surface, a member having an end surface having a shape complementary to such a shape may be used.

When two or more thin plate-like or thin film-like members are laminated and joined, one set or a plurality of sets of roller pairs are used as the pressing member and / or the energizing member in the pressing / energizing means. The members may be continuously conveyed through these spaces. When joining pipe-shaped members, use a bobbin-shaped roller as a pressing member and / or
Alternatively, it may be used as a current-carrying member. Furthermore, in order to apply the pressing force uniformly at each joint surface position, a conductive cushion (coil spring or the like) is provided between the electrode and the joint member.
Alternatively, it may be arranged between the pressing member and the electrode.

The present invention can of course be applied to the case where three or more members are simultaneously joined. In the case of a rod-shaped member, a plurality of joint surfaces can be joined at the same time by pressing a plurality of rods in series while abutting each other. Further, by arranging a plurality of such members joined in series in parallel and pressing and energizing them at the same time, a larger number of members can be joined at the same time.

The pressing direction can be applied not only in the uniaxial direction but also in the multiaxial direction. For example, a pressing force may be applied to the joint surface from the orthogonal direction. Alternatively, it is also possible to add from an oblique direction.

Next, the members to be joined according to the present invention are
Metals such as iron, iron-based alloys, nickel, titanium, cast iron,
Non-ferrous metals such as copper, aluminum, zinc, non-ferrous alloys, N
Special alloys such as i-base heat-resistant alloys, shape memory alloys, heat-resistant alloys, vibration-proof alloys, sound-proof alloys, shield materials, etc., spark plasma sintered bodies, Peltier structure sintered bodies, hot pressed sintered bodies, and other powder sintered bodies, There are members such as ceramics, semiconductors, and single crystal materials that exhibit conductivity at high temperatures.

The joining member may have any shape, for example, bulk (solid), thin plate (thin film), pipe, corrugated, granular, etc. It is also possible to join different shapes to each other.

On the other hand, the solid-state joining method using pulsed current according to the present invention comprises a joining surface treatment step of forming a thin film on at least one of the joining surfaces of at least two members to be joined, and a joining surface of the members. A butting step of butting each other, and pressing the butted joint surfaces against each other,
It is characterized by including a pressurizing / energizing step of temporarily joining the joining surface by passing a pulse current through the joining surface, and a heat treatment step of heat treating the member in the temporarily joining state under a predetermined temperature condition. I am trying.

Here, at least a part of the components of the thin film may be the same as the bonding surface on which the thin film is formed.

The thin film may contain a component capable of permeating and diffusing into the joint surface.

Further, the thin film may contain a reducing component.

The thickness of such a thin film is 0.01 to 10
It is desirable to set it within the range of μm.

The thin film can be formed by a sputter deposition method.

Next, the surface roughness of the joint surface is Ra = 0.3.
It is desirable to use the above mirror surface.

In the pressing / energizing step, 1 to 70
It is desirable to press the joint surface with a pressing force within the range of 0 MPa.

Further, in the pressing / energizing step, the duty ratio is 50% or more, the voltage is 100 V or less, and the current value is 1
It is desirable to pass a pulse current in the range of 00A to 50,000A.

Furthermore, the heat treatment temperature in the heat treatment step is 55 which is the melting point of the members to be joined having the lowest melting point.
It is desirable that the temperature is within the range of 90% to 90%. In this case, generally, the heat treatment time in the heat treatment step is 6
It is set to 0 minutes or less. Further, it is desirable that the heat treatment process is performed in vacuum.

[0049]

EFFECTS OF THE INVENTION According to the solid-state joining method and joining apparatus using pulsed current of the present invention, the joining strength of the joining surface is improved as compared with the conventional method, and the joining strength is as strong as the base material strength of the joining member. It was confirmed that a reliable joined state can be formed by.

[Brief description of drawings]

FIG. 1 is a schematic flowchart showing a solid-state bonding method by pulsed current according to the present invention.

FIG. 2 is an explanatory view schematically showing a state transition of a thin film formed on a joint surface in a solid-state joining method using pulsed current according to the present invention.

FIG. 3 is an explanatory view schematically showing a state transition of a thin film formed on a joint surface in a solid-state joining method using pulsed current according to the present invention.

FIG. 4 is a schematic configuration diagram showing an example of a schematic configuration of a joining device using pulsed current according to the present invention.

[Explanation of symbols]

S0 Bonding surface treatment process S1 match process S2 forced heating process S3 pressing / pulse energization process S4 heat treatment process 1 and 2 joining members 1a, 2a Bonding surface 3, 4, 6, 7 Thin film formed on the bonding surface 5, 5a, 8, 8a Bonding interface 10 joining device 11 Pressing means 12 External heating means 13 energizing means 14 Vacuum device 15 Processing room 21 heating element 22 cover 23 Guide mechanism 31, 32 electrodes 33 Pulse current supply source

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[Procedure amendment]

[Submission date] March 20, 2002 (2002.3.2)
0)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

Claims (39)

[Claims] 1. A butting step of butting the joining surfaces of at least a first member and a second member, which are objects to be joined, with each other, and a forced heating step of locally forcibly heating the joining surfaces of the butted members from outside. A pressing / pulse energization step of temporarily joining the joined surfaces by pressing a pulsed current through the joined surfaces while mutually pressing the joined surfaces in a heated state, and a predetermined temperature condition for the member in the temporarily joined state. Solid-state bonding method by pulsed current application, which includes a heat treatment step of heat treatment under the following conditions. 2. The method according to claim 1, wherein in the forced heating step, the joining surface is heated to a temperature within a range of 55% to 90% of a melting point of a joining target member having a lowest melting point. A solid-state joining method using pulsed current. 3. The solid bonding method according to claim 2, wherein the heating time in the forced heating step is 60 minutes or less. 4. The solid-state joining method by pulse energization according to claim 1, wherein in the pressing / pulse energizing step, the joining surface is pressed with a pressing force within a range of 1 to 700 MPa. 5. The duty ratio is 50% in the pressing / pulse energizing step according to claim 1.
As described above, the voltage is 100 V or less, the current value is 100 A to 50,
A solid-state joining method by pulsed current application, characterized in that a pulsed current within a range of 000 A is flown. 6. The pulse according to claim 1, wherein the heat treatment temperature in the heat treatment step is a temperature within a range of 55% to 90% of a melting point of a joining target member having a lowest melting point. Solid-state joining method by energization. 7. The solid-state joining method according to claim 6, wherein the heat treatment time in the heat treatment step is 60 minutes or less. 8. The solid-state bonding method according to claim 1, wherein the heat treatment step is performed in a vacuum. 9. The joint according to claim 1, further comprising, prior to the butting step, performing surface treatment on at least one of the joint surfaces of the first member and the joint surface of the second member. A solid-state joining method by pulsed current application, which comprises a surface treatment step. 10. The solid-state joining method according to claim 9, wherein the joining surface treatment step includes a polishing treatment for increasing the smoothness of the joining surface. 11. The surface roughness of the joint surface according to claim 10, wherein Ra = 0.3.
A solid-state joining method using pulsed current, characterized by finishing to the above mirror surface. 12. The solid-state joining method by pulse current application according to claim 9, wherein the joining surface treatment step includes a washing treatment for washing the joining surface. 13. The solid-state joining method according to claim 9, wherein the joining surface treatment step includes a treatment of forming a thin film on the joining surface. 14. The solid-state joining method according to claim 13, wherein at least a part of the components of the thin film is the same as the joining surface on which the thin film is formed. 15. The solid-state bonding method according to claim 13, wherein the thin film contains a component capable of permeating and diffusing into the bonding surface. 16. The solid-state bonding method according to claim 13, wherein the thin film contains a reducing component. 17. The solid-state bonding method according to claim 13, wherein the thin film has a thickness within a range of 0.01 to 10 μm. 18. The solid-state bonding method according to claim 13, wherein the thin film is formed by a sputter deposition method. 19. The process for processing a joint surface according to claim 9, wherein the joint surface of the first member and the joint surface of the second member are processed into complementary joint surface shapes so as to be in close contact with each other. A solid-state joining method by pulsed current application, which comprises a treatment of: 20. A joining device for joining at least a first member and a second member by the solid-state joining method using pulsed current according to claim 1, wherein the joining surface of the first member and the second member are joined together. Holding means for holding the joint surfaces in contact with each other, and pressing means for pressing these joint surfaces with a predetermined pressing force; external heating means for locally forcibly heating the joint surfaces in the butted state; A joining apparatus comprising: an energizing means for passing a pulse current through a joining surface; and a heat treatment means for heat treating the first and second members in a temporary joining state. 21. The heating element of the external heating means according to claim 20, wherein any one or a combination of electric resistance heating, microwave heating, glow discharge heating, high frequency heating, electric current heating, impulse heating and infrared heating is used. A joining device, which is a heating element. 22. The solid bonding apparatus according to claim 21, wherein the external heating means is capable of locally forcibly heating the bonding surface and heating the entire member in the butted state. 23. The joint according to claim 22, wherein the external heating means includes a cover surrounding the joint surface in a butt state and the heating element built in the cover. apparatus. 24. The joining apparatus according to claim 23, wherein the external heating means includes a cover guide mechanism capable of adjusting at least one of the arrangement position and the angle of the cover. 25. The first unit according to any one of claims 22 to 24, which is held in a butted state by the pressing means.
And a processing chamber in which the second member is disposed, and the local forced heating, pressing and heat treatment are performed in the processing chamber. 26. The joining apparatus according to claim 25, wherein the external heating means and the heat treatment means are combined. 27. The method according to claim 26, wherein the external heating means provided with a single power source is switched and controlled to perform the local forced heating on the joint surface and the overall heating during the heat treatment. Joining device. 28. A joining surface treatment step of forming a thin film on at least one of the joining surfaces of at least two members to be joined, and a butting step of butting the joining surfaces of the members together. A pressure / pulse energization step of temporarily joining the joining surfaces by applying a pulse current through the joining surfaces while pressing the joining surfaces against each other; Solid-state bonding method by pulsed current application, including a heat treatment step of heat treatment in step. 29. The solid-state joining method according to claim 28, wherein at least a part of the components of the thin film is the same as the joining surface on which the thin film is formed. 30. The solid-state bonding method according to claim 28, wherein the thin film contains a component capable of permeating and diffusing into the bonding surface. 31. The solid-state bonding method according to claim 28, wherein the thin film contains a reducing component. 32. The solid-state bonding method according to claim 28, wherein the thin film has a thickness within a range of 0.01 to 10 μm. 33. The solid-state joining method according to claim 28, wherein the thin film is formed by a sputter deposition method. 34. The solid-state joining method according to any one of claims 28 to 33, wherein the surface roughness of the joint surface is a mirror surface with Ra = 0.3 or more. 35. The solid-state joining method by pulse energization according to claim 28, wherein in the pressing / energizing step, the joint surface is pressed with a pressing force within a range of 1 to 700 MPa. 36. The duty ratio of 50% or more in the pressing / energizing step according to claim 28,
Voltage is 100V or less, current value is 100A to 50,000
A solid-state joining method by pulsed current application, characterized in that a pulsed current within the range of A is flown. 37. The pulse according to claim 28, wherein a heat treatment temperature in the heat treatment step is a temperature within a range of 55% to 90% of a melting point of a joining target member having a lowest melting point. Solid-state joining method by energization. 38. The solid-state bonding method according to claim 37, wherein the heat treatment time in the heat treatment step is 60 minutes or less. 39. The solid-state bonding method according to claim 28, wherein the heat treatment step is performed in vacuum.